This invention relates to a corrugated tube for fitting on a wire harness (a bundle of wires) or the like, and more particularly to a corrugated tube of the overlapping type in which a lap portion, formed in a projected manner at one of opposed side edges of a slit formed in the corrugated tube along an axis thereof, is laid on an inner peripheral face of the other side edge portion,
Generally, in a corrugated tube used for bundling and protecting transmission/distribution wires of an electronic equipment, a wire harness of an automobile or others, spiral or annular ridge portions are formed continuously on an outer peripheral face of a resin tube to form a bellows-like construction, thereby imparting bendability to the corrugated tube.
In order that a wire harness or the like can be easily inserted into and removed from the corrugated tube for protecting the wire harness, a slit is formed in the corrugated tube, and extends along the axis thereof.
However, when such a corrugated tube is bent along an installation path, the slit is partially opened in the vicinity of a central portion of the bent portion, and the inserted wire harness or be like projects outwardly through the opened portion of the slit, thus adversely affecting the inserting operation, and besides there is a fear that the wire harness is caught by the opposed side edges of the slit, so that an insulating sheath of the wire harness is damaged.
Therefore, usually, an insulating tape is wound on the outer peripheral face of the corrugated tube, thereby preventing the slit from being opened. However, there has been encountered a problem that this tape-winding operation requires much time and labor.
In order to solve the above problems with the corrugated tube, there have been proposed various corrugated tubes of the overlapping type in which a slit will not be opened to form an opened portion even when the corrugated tube is bent.
In a corrugated tube 1 of the overlapping type shown in FIGS. 7 and 8, a plate-like lap portion 8, formed in a projected manner at one of opposed side edges of a slit 5 formed along an axis of a tube body 3, is laid on (laps over) an inner peripheral face of the other side edge portion of the slit 5 so that a wire harness W will not be exposed to outside even when the corrugated tube is bent A tape-winding operation is not necessary.
In the corrugated tube 1, the lap portion 8, laid on the inner peripheral face of the other side edge portion of the slit, has a distal end edge extending straight in the axial direction.
Therefore, when inserting the wire harness W into the corrugated tube after expanding the slit 5, the wire harness W is less liable to be caught by the distal end edge of the lap portion 8, and the harness-inserting operation can be effected smoothly. And besides, there is no fear that the distal end edge of the lap portion 8, laid on the inner peripheral face of the corrugated tube 1, damages an insulating sheath of the inserted wire harness W.
For forming the above corrugated tube 1, first, a tube-like molten resin is extruded from a die into a tubular mold having a predetermined molding face formed on an inner peripheral face thereof, and either by applying pressurized air to the inside of this tube or by applying vacuum to the outer side of this tube, ridge and grooves, formed at the molding fate, are transferred to the tube-like molten resin, thereby continuously forming a long tube body 3.
The tube body 3, molded into an integral construction, includes a plate-like portion 7, extending along the axis thereof, and a bellows portion 9 having a series of arcuate ridge portions 10 which are formed in a bulged manner on an outer peripheral face of the tube body 3 except the plate-like portion 7, and are arranged along the axis of the tube body 23.
Then, the straight slit 5 is formed in the plate-like portion 7 along the axis of the tube body, so that the plate-like lap portion 8 is formed at one of the opposed side edges of the slit 5 in a projected manner.
Then, the corrugated tube 1 is formed by heat into such a shape that the lap portion 8 laps on the inner peripheral face of the other side edge portion of the slit 5, thereby forming the corrugated tube 1 of the overlapping type as shown in FIG. 9.
In the above corrugated tube 1, however, the lap portion 8 is formed into a plate-like shape, and besides end walls 12 and 14 are formed respectively at circumferential end portions of each ridge portion 10 opposed to each other with the slit 5 lying therebetween.
When bending the corrugated tube 1 along an installation path, the lap portion 8, which is formed into the plate-like shape, can not be easily bent, and the corrugated tube I itself can not be easily bent and therefore there has been encountered a problem that the installation operation can be adversely affected.
Particularly when the corrugated tube 1 is bent in such a manner that the lap portion 8 is curved inwardly (curved convexly downwardly as shown in FIGS. 10A and 10B), the lap portion 8, together with the end walls 12 and 14 (which are parallel to the bending direction, and have high rigidity), provides a resistance to the bending, and therefore the flexibility of the corrugated tube 1 is not good.
In the corrugated tube 1 of the overlapping type in which the lap portion 8 is laid on the inner peripheral face of the other side edge portion of the slit, when the wire harness W is to be inserted into this corrugated tube after expanding the slit 5, the slit 5 must be opened wide while displacing the lap portion 8, and therefore there has been encountered a problem that the operation for inserting the wire harness W requires much time and labor.
It is therefore an object of this invention to provide a corrugated tube in which a flexibility can be enhanced though having a lap portion, and a wire harness or the like can be easily received therein.
In order to achieve the above object, according to the present invention, there is provided a corrugated tube comprising:
a tubular body, provided with a first slit which extends in an axial direction of the tubular body, and the tubular body formed with a plurality of hollow ridge portions extending in a circumferential direction of the tubular body on an outer peripheral face of the tubular body to form a bellows portion, and
a lap portion, protruded from at least one of opposed end portions of the tubular body separated by the first slit the lap portion extending along the first slit;
wherein, the lap portion is provided with a second slit which extends in the circumferential direction of the tubular body.
In this construction, the lap portion comprises a plurality of juxtaposed lap piece portions which are separated from one another by the second slits, and therefore the lap portion is reduced flexural rigidity in the axial direction, and can be easily deformed with a stress in a bending direction.
Therefore, the lap portion of the tubular body will not provide a large resistance to the bending of the corrugated tube, and the flexibility of the corrugated tube is enhanced.
The lap piece portions can be flexed more easily as compared with the related lap portion, extending in the axial direction, and these lap piece portions can be flexed independently of one another.
Therefore, when inserting a wire harness or the like into the corrugated tube after expanding the slit, the harness-inserting operation can be effected smoothly.
Preferably, the second slit is extended toward and on the ridge portion.
In this construction, the end portions of the ridge portions cut by the second slit are reduced in rigidity, and therefore can be easily deformed with a stress in the axial direction.
When the tubular body is bent, relieve from bent can be secured also at the end portions of the ridge portions, and the flexibility of the corrugated tube, having the lap portion, can be further enhanced.